Time filter



Oct. 26, 1965 L. KLEIN ETAL 3,214,693,

TIME FILTER Original Filed April 17', 1957 TAPE CHANNEL 2 05cm! COUNTER 4 l3 2 454 /31 I/ 7 4,6 I .1 .1 1L

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MARTIN L. KLEIN HARRY G. MORGAN BY RIZHARD B. USH

United States Patent 3,214,693 TIME FILTER Martin L. Klein and Harry C. Morgan, Woodland Hills, and Richard B. Rush, Granada Hills, Califl, assignors to North American Aviation, Inc.

Original application Apr. 17, 1957, Ser. No. 653,455. Divided and this application Jan. 26, 1961, Ser. No. 90,594

3 Claims. (Cl. 32848) This application is a division of patent application 653,455. It relates to data handling and concerns particularly a time filter that selects a dead time-interval that extends for a predetermined interval after the initiation of operations; followed by a slice of live-time having a predetermined duration; after which the timefilter efiectively disables itself.

Situations requiring a sequence of this sort may arise in many fields; i.e., during a rocket-engine test. Here various pieces of recording equipment must be warmed up for predetermined dead intervals of time during the count-down sequence, without actual-1y recording; otherwise they would be recording information that is useless and undesirable, in addition to which the undesired recording operation wastes recording space on the tapes. After this dead time-interval the incoming information is recorded, and then the equipment assumes a stand-by mode of operation.

The instant invention solves this problem by having two intervals of time; the first, preset time-interval, being of an independently selectable length, and may be dead time during which no information is recorded; the second, elapsed time-interval also being of an independently selectable length, and may be a live slice of time during which information is recorded.

It is an object of the present invention to provide a time filter for enabling the user to preset the start of recording and the interval of recording in cases where only a given portion of data is to be used.

Broadly speaking, the invention comprises a predetermined-counter into which two independently-adjustable preset values may be sequentially inserted. The operation of the invention is such that a start-switch sets a flipflop to one state, and simultaneously inserts one of the preset values into the computer. Incoming pulses applied to the computer produce a dead-time interval determined by the first inserted value; at the termination of which time-interval the counter produces an output pulse that sets the fiip-fiop to its other state. In this second state, the flip-flop produces an output signal, and simultaneously inserts the seocnd value into the computer. Incoming pulses applied to the computer now produce a live-time-interval determined by the second inserted value. At the end of the second elapsed-time interval, the output signal from the computer resets the flip-flop to its first state, the flip-flop remaining at this first state until the start-switch is again energized.

In this way, the dead time interval always starts at zero, and is always measured in its entirety; after which an elapsed time is measured; after which the circuit reverts to its original setting, but does not produce any output signal until the start-switch is again energized.

A better understanding of the invention will be afiorded by the following detailed description, considered in conjunction with the only drawing, which is a schematic diagram of the time filter.

The time filter is illustrated in greater detail in the illustration. It is essentially a preset counter 411-416 with two sets of presetting decimal switch banks, one 441 through 447 for presetting the start of dead time interval and the other 471 through 477 for presetting the interval of recording desired (elapsed time). The counter itself comprises a plurality of modulus 1.0 counting circuits 411, 412, 413, 414, 4-15 and 416 which provide a maximum count of 9,999,999 eighteen bit words. It is to be understood, however, that for a greater or smaller count, a difierent number of counting circuits 411 to 416 would be employed. The internal circuits of the counting circuit 411 indicated fragmentarily in the illustration include four bistable valve circuits, 417, 418, 419 and 420 arranged to count 10 in binary fashion. These are the conventional cascaded type each with presetting connections. For the unit 411 presetting connections are provided, represented schematically by a line 422. There is an input connection 423 from the second channel output connection 406 of the tape play back package 401.

Each bistable circuit 417-420 of counting circuit 411 has an output connected to the input of the next bistable circuit such as the connection 424 between bistable circuits 417 and 418, the connection 425 between the bistable circuits 418 and 419, and the connection 426 be tween the bistable circuits 419 and 420. There is an output connection 427 from the counting circuit 411 serving as the input connection to the counting circuit 412. Similarly there are other connections 428, 429, 430, 431 and 432 successively, between the series of counting circuits 412-416 inclusive.

Record starting and stopping control lines 433 and 434 are provided which are controlled by a flip-flop circuit 435 having an input or tripping connection 436 from the output of the final counting circuit 416. Preferably, amplifiers of suitable type such as thyratron amplifiers 437 and 438 are interposed between the signal output terminals of the valves of the bistable valve circuit 435 and the record stop and start lines 433 and 434.

For setting in the dead-time interval, schematically represented rnultipoint dead'time preset switches 441, 442, 443, 444, 445, 446 and 447 are provided which are connected to counter cables 422, 451, 452, 453, 454, 455 and 456 for the requisite presetting switch connections.

Preferably diodes 457, 458, 459, 460,, 461, 462 and 463 are connected in series with the switches 441447, respectively, to a common line 465 which is connected to the output of a thyratron pulse generator 466. There is a manual push button preset switch 467 for firing the thyratron 466 to preset the counter through the line 465. A line 448 is also connected to the switch 467 for resetting valve 449 of the flip-flop unit 435.

For presetting the elapsed time, preset switches 471 to 477, inclusive, are provided with interposed diodes 481 to 487, respectively.

The switches 441447 and 471-477 are arranged and connected in the manner described by Paul Bey in Tele- Tech, July 1955, pages 72-73, in an article entitled Time and Frequency Measurements With a New Preset Counter. The dead-time presetting switches 441-447 are set for a value such that the last counting: circuit of the counter will trip at the desired start time, whereas the elapsed-time presetting switches 471477 are set to cause the supply of data to stop after the desired time slice of data has been supplied.

A common line 478 of the diodes 481-487 is connected through a line 479 to the output of the thyratron amplifier 437 for causing the starting pulse supplied by the flip-flop circuit 435 to reset the counter for elapsed time according to the settings of switches 471-477.

Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of this invention being limited only by the terms of the appended claims.

3 We claim: 1. A time filter for providing a single dead-time interval, followed by a single elapsed-time interval, comprising:

a counter;

a start-switch;

a dead-time preset switch;

means, comprising said start-switch, for assuring that means, comprising said start-switch, for presetting said counter through said dead-time preset switch to cause input pulses to be applied to saidcounter for a dead time interval, at the end of which dead time interval the output signal from said counter resets said flipflop to its second state;

an elapsed-time preset switch; and

means for causing the second-state signal from said fiip-flop to preset said counter through said elapsedtime preset switch to cause input pulses to be applied to said counter for the duration of said elapsedtime interval, at the end of which elapsed-time in terval the output signal from said counter sets said flip-flop to its first state, said flip-flop now remaining in its first state until said start-switch is again energized.

2. A time filter for providing a single dead-time interval, a single elapsed-time interval, and a time interval of indeterminate duration, comprising:

a counter;

a start-switch;

a dead-time preset switch;

means, comprising said start-switch, for assuring that said flip-flop is in its first state;

means for causing said start-switch to preset said counter through said dead-time preset switch to cause said input pulse to be applied to said counter for the entire duration of a predetermined dead time interval, at the end of which dead time interval the output signal from said counter resets said flip-flop to its second statewhereby a single dead time interval is produced;

an elapsed-time preset switch;

means for causing the second-state signal from said flip-flop to preset said counter through said elapsedtime preset switch to cause said input pulses to be applied to said counter for the duration of said elapsed-time interval, at the end of which elapsed time interval the output signal from said counter sets said flip-flop to its first state; and

means, comprising a connection between the output of said counter and the input of said flip-flop, for causing the output signal from said counter to reset said flip-flop to its first state for a time interval of indetermined duration, said flip-flop now remaining in its first state until said start switch is again energized.

3. A time filter for controlling the recording on a recorder of a portion of a quantity of information elected as to initiation and duration, comprising:

a counter for receiving input pulses synchronized with the information to be recorded, said counter being capable of operating two independently predetermined modes and an un-predetermined mode;

a start-switch;

a pulse generator;

21 dead-time preset switch;

means, comprising said start-switch, for assuring that said flip-flop is in its first state, said first state of said flip-flop producing a record-stop signal;

means, comprising said pulse generator, for presetting said counter through said dead time preset switch to cause said computer to operate in a first deadtime mode to operation, the input pulses being applied to said counter for the entire duration of a dead-time interval, at the end of which dead-time interval the output signal from said counter resets said flip-flop to its second state, said second-state producing a record-start signal;

an elapsed-time preset switch;

means for causing the second-state signal from said flip-flop to preset said counter through said elapsedtime preset switch to cause said computer to operate in a second elapsed-time mode of operation, said input pulses now being applied to said counter for the duration of said elapsed-time interval, at the end of which elapsed time interval the output signal from said counter sets said flip-flop to its first state, the first-state signal of said flip-flop now causing said counter to operate in its un-predetermined mode of operation, and re-establishing said record-stop signal, said flip-flop now remaining in its first-state until said start-switch is again energized.

References (Zited by the Examiner UNITED STATES PATENTS 2,493,627 1/50 Grosdotf 32848 2,521,774 9/50 Bliss 328-51 2,563,841 8/51 Jensen 32825 2,669,390 2/54 Manley 32852 2,743,419 4/56 Chatterton et al. 328136 2,749,437 6/56 Parr 32848 2,771,551 11/56 Hampton 328-50 2,883,531 4/59 Anderson 328 2,970,226 1/61 Skelton et al. 307-88.5

OTHER REFERENCES Predetermined Counters, by John J. Wild, Electronics, March 1947, pages 120423.

JOHN W. HUCKERT, Primary Examiner. 

1. A TIME FILTER FOR PROVIDING A SIGNALE DEAD-TIME INTERVAL, FOLLOWED BY A SINGLE ELAPSED-TIME INTERVAL, COMPRISING: A COUNTER; A FLIP-FLOP; A START-SWITCH; A DEAD-TIME PRESET SWITCH; MEANS, COMPRISING SAID START-SWITCH, FOR ASSURING THAT SAID FLIP-FLOP IS IN A FIRST STATE; MEANS, COMPRISING SAID START-SWITCH, FOR PRESETTING SAID COUNTER THROUGH SAID DEAD-TIME PRESET SWITCH TO CAUSE INPUT PULSES TO BE APPLIED TO SAID COUNTER FOR A DEAD TIME INTERVAL, AT THE END OF WHICH DEAD TIME INTERVAL THE OUTPUT SIGNAL FROM SAID COUNTER RESETS SAID FLIPFLOP TO ITS SECOND STATE; AN ELAPSED-TIME PRESET SWITCH; AND MEANS FOR CAUSING THE SECOND-STATE SIGNAL FROM SAID FLIP-FLOP TO PRESET SAID COUNTER THROUGH SAID ELAPSEDTIEM PRESET SWITCH TO CAUSE INPUT PULSES TO BE APPLIED TO SAID COUNTER FOR THE DURATION OF SAID ELAPSEDTIME INTERVAL, AT THE END OF WHICH ELAPSED-TIME INTERVAL THE OUTPUT SIGNAL FROM SAID COUNTER SETS SAID FLIP-FLOP TO ITS FIRST STATE, SAID FLIP-FLOP NOW REMAINING IN ITS FIRST STATE UNITL SAID START-SWITCH IS AGAIN ENERGIZED. 